Build RecyclerView inline

app/src/main/java/androidx/recyclerview/widget/ItemTouchUIUtilImpl.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.recyclerview.widget;
+
+import android.graphics.Canvas;
+import android.os.Build;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.core.view.ViewCompat;
+import androidx.recyclerview.R;
+
+/**
+ * Package private class to keep implementations. Putting them inside ItemTouchUIUtil makes them
+ * public API, which is not desired in this case.
+ */
+class ItemTouchUIUtilImpl implements ItemTouchUIUtil {
+    static final ItemTouchUIUtil INSTANCE =  new ItemTouchUIUtilImpl();
+
+    @Override
+    public void onDraw(
+            @NonNull Canvas c,
+            @NonNull RecyclerView recyclerView,
+            @NonNull View view,
+            float dX,
+            float dY,
+            int actionState,
+            boolean isCurrentlyActive
+    ) {
+        if (Build.VERSION.SDK_INT >= 21) {
+            if (isCurrentlyActive) {
+                Object originalElevation = view.getTag(R.id.item_touch_helper_previous_elevation);
+                if (originalElevation == null) {
+                    originalElevation = ViewCompat.getElevation(view);
+                    float newElevation = 1f + findMaxElevation(recyclerView, view);
+                    ViewCompat.setElevation(view, newElevation);
+                    view.setTag(R.id.item_touch_helper_previous_elevation, originalElevation);
+                }
+            }
+        }
+
+        view.setTranslationX(dX);
+        view.setTranslationY(dY);
+    }
+
+    private static float findMaxElevation(RecyclerView recyclerView, View itemView) {
+        final int childCount = recyclerView.getChildCount();
+        float max = 0;
+        for (int i = 0; i < childCount; i++) {
+            final View child = recyclerView.getChildAt(i);
+            if (child == itemView) {
+                continue;
+            }
+            final float elevation = ViewCompat.getElevation(child);
+            if (elevation > max) {
+                max = elevation;
+            }
+        }
+        return max;
+    }
+
+    @Override
+    public void onDrawOver(
+            @NonNull Canvas c,
+            @NonNull RecyclerView recyclerView,
+            @NonNull View view,
+            float dX,
+            float dY,
+            int actionState,
+            boolean isCurrentlyActive
+    ) {
+    }
+
+    @Override
+    public void clearView(@NonNull View view) {
+        if (Build.VERSION.SDK_INT >= 21) {
+            final Object tag = view.getTag(R.id.item_touch_helper_previous_elevation);
+            if (tag instanceof Float) {
+                ViewCompat.setElevation(view, (Float) tag);
+            }
+            view.setTag(R.id.item_touch_helper_previous_elevation, null);
+        }
+
+        view.setTranslationX(0f);
+        view.setTranslationY(0f);
+    }
+
+    @Override
+    public void onSelected(@NonNull View view) {
+    }
+}